Monday, June 21, 2010
I recently came across an article about a professor who has come up with a novel way to make bricks. Concrete in general and bricks in specific require a lot of energy to produce. The raw materials have to be heated to very high temperatures to achieve the right chemical reactions. All that energy costs money and has a high environmental impact. Professor Ginger Dosier has come up with a possible solution. She fills a mold with sand and introduces a special bacteria and a solution containing urea, a common waste product. Over the next four to seven days, the bacteria consumes the urea and produces calcium carbonate, locking the sand particles together and creating a sort of synthetic sandstone. All this happens biologically at room temperature.
Of course, I am a bit of a chemistry geek and happen to know that urea ((NH2)2CO) and sand (usually SiO2) don’t contain any calcium, which makes the formation of calcium carbonate (CaCO3) a little tricky. However, I am willing to assume that there is some sort of nutrient broth introduced that the article above failed to mention. If any of you out there have any further details on this, I’d love to hear them.
I find this technology promising as concrete production is responsible for about 5-8% of greenhouse gas production worldwide. Most of those gasses are produced as a result of the heating of the raw materials used in concrete, but the chemical reactions that produce concrete also produce carbon dioxide. Fortunately, there are others tackling this problem as well. In England, engineers have come up with a type of concrete that is based on magnesium silicates instead of calcium carbonate. The interesting thing about this concrete is that it not only uses less heat to produce, but it actually consumes carbon dioxide from the atmosphere as it cures, making it carbon-negative.
Of course, it may be years before these products become widely available as materials like this need to undergo extensive testing in order to develop standards for mix design and production. Then those standards need to be adopted by regulatory agencies. That all takes time. However, the Italians have discovered a kind of concrete that actually scrubs the pollutants from the air. The benefit of this is that it is only a minor modification of existing concrete and thus doesn’t need extensive testing. They discovered that when titanium dioxide, which is a white dye often used in foods, is mixed in with the concrete, it reacts with the sunlight, producing a catalytic reaction that breaks down carbon monoxide and nitrogen dioxide in the atmosphere. While it isn’t a cure for carbon dioxide emissions, it can help with air quality.